Method, terminal, and system for realizing device to device communication

ABSTRACT

A communication method includes: acquiring a wireless network temporary identifier used for device to device communication; receiving transmission grant information scrambled through the wireless network temporary identifier used for the device to device communication; and performing the device to device communication according to descrambled transmission grant information. A terminal may realize the D2D communication according to the wireless network temporary identifier used for performing the device to device communication and the transmission grant information by sending, to the terminal, the wireless network temporary identifier used for performing the device to device communication and the transmission grant information, thereby satisfying a requirement of D2D data transmission between terminals.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/226,181, filed on Mar. 26, 2014, which is a continuation ofInternational Application No. PCT/CN2012/080812, filed on Aug. 31, 2012,which claims priority to Chinese Patent Application No. 201110297125.1,filed on Sep. 30, 2011, all of which are hereby incorporated byreference in their entireties.

FIELD OF THE INVENTION

Embodiments of the present invention relate to the field ofcommunications, and in particular, to a method, terminal, and system forrealizing device to device communication.

BACKGROUND OF THE INVENTION

A device to device (device to device, D2D for short) technology is acommunications technology of direct data exchange between devices undercontrol of a mobile network. The D2D technology under systems such as along term evolution (long term evolution, LTE for short) system is stillin a conceptual stage, and no standardization work is started.

SUMMARY OF THE INVENTION

A technical problem to be solved by embodiments of the present inventionis how to realize device to device communication.

In order to solve the technical problem, an embodiment of the presentinvention provides a method for realizing device to devicecommunication, which includes:

acquiring a wireless network temporary identifier used for device todevice communication;

receiving transmission grant information scrambled through the wirelessnetwork temporary identifier used for the device to devicecommunication; and

performing the device to device communication according to descrambledtransmission grant information.

Accordingly, an embodiment of the present invention further provides aterminal, which includes:

an acquisition module, configured to acquire a wireless networktemporary identifier used for device to device communication andtransmission grant information scrambled through the wireless networktemporary identifier used for the device to device communication; and

a processing module, configured to perform the device to devicecommunication according to descrambled transmission grant information.

Accordingly, an embodiment of the present invention further provides acommunication system, which includes a first terminal, a secondterminal, and a base station, where the first terminal and the secondterminal each are configured to acquire a wireless network temporaryidentifier which is sent by the base station and used for device todevice communication, receive transmission grant information which issent by the base station and scrambled through the wireless networktemporary identifier used for the device to device communication, andperform the device to device communication according to descrambledtransmission grant information.

Implementation of the embodiments of the present invention has thefollowing beneficial effects:

By sending, to the terminal, the wireless network temporary identifierused for performing the device to device communication and thetransmission grant information, the terminal may realize the D2Dcommunication between the terminals according to the wireless networktemporary identifier used for performing the device to devicecommunication and the transmission grant information, thereby satisfyinga requirement of D2D data transmission between users.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of a communication systemaccording to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a terminal according to anembodiment of the present invention;

FIG. 3 is a schematic flow chart of Embodiment 1 of a method forrealizing device to device communication of the present invention;

FIG. 4 is a schematic flow chart of Embodiment 2 of a method forrealizing device to device communication of the present invention;

FIG. 5 is a schematic flow chart of Embodiment 3 of a method forrealizing device to device communication of the present invention;

FIG. 6 is a schematic flow chart of Embodiment 4 of a method forrealizing device to device communication of the present invention;

FIG. 7 is a schematic flow chart of Embodiment 5 of a method forrealizing device to device communication of the present invention; and

FIG. 8 is a schematic flow chart of Embodiment 6 of a method forrealizing device to device communication of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following clearly describes the technical solutions in theembodiments of the present invention with reference to the accompanyingdrawings in the embodiments of the present invention. Apparently, thedescribed embodiments are merely a part rather than all of theembodiments of the present invention. All other embodiments obtained bypersons skilled in the art based on the embodiments of the presentinvention without creative efforts shall fall within the protectionscope of the present invention.

FIG. 1 is a schematic structural diagram of a communication systemaccording to an embodiment of the present invention. The systemdescribed in this embodiment includes a base station 11, a firstterminal 21, and a second terminal 22.

When the first terminal 21 and the second terminal 22 need to performD2D communication, the first terminal 21 and the second terminal 22 eachare configured to acquire a wireless network temporary identifier whichis sent by the base station 11 and used for the D2D communication,receive transmission grant information which is sent by the base station11 and scrambled through the wireless network temporary identifier usedfor the D2D communication, and perform the device to devicecommunication according to the descrambled transmission grantinformation.

The base station 11 may send, to the first terminal 21 and the secondterminal 22 through a radio resource control (radio resource control,RRC for short) message, the wireless network temporary identifier usedfor performing the D2D communication and the transmission grantinformation, where the transmission grant information may be an uplinkgrant or a downlink grant.

The first terminal 21 and the second terminal 22 perform the D2Dcommunication according to the descrambled transmission grantinformation by: acquiring transmission carrier information, andperforming, on a carrier indicated by the transmission carrierinformation, the device to device communication according to thetransmission grant information. The acquiring the transmission carrierinformation includes: acquiring the transmission carrier informationsent by the base station 11, where the base station 11 may send thetransmission carrier information through the RRC message; or acquiringthe transmission carrier information according to the transmission grantinformation.

The first terminal 21 or the second terminal 22 is further configured toacquire one wireless network temporary identifier used for the device todevice communication; and the transmission grant information includesdevice to device transmission direction indication information.

Alternatively, the first terminal 21 or the second terminal 22 isfurther configured to acquire two wireless network temporary identifiersused for the device to device communication; and the wireless networktemporary identifier which is sent by the base station and used for thedevice to device communication is applicable to a device to devicetransmission direction.

Alternatively, the first terminal or the second terminal is furtherconfigured to acquire cell wireless network temporary identifiers of thefirst terminal and the second terminal; and the transmission grantinformation includes indication information of the device to devicecommunication.

By sending, to the terminal, the wireless network temporary identifierused for performing the D2D communication and the transmission grantinformation, the terminal may realize the direct D2D communicationbetween the terminals according to the wireless network temporaryidentifier used for performing the D2D communication and thetransmission grant information, thereby satisfying a requirement of D2Ddata transmission between users.

FIG. 2 is a schematic structural diagram of a terminal according to anembodiment of the present invention, and the first terminal 21 and thesecond terminal 22 in FIG. 1 that act as the terminals may have the samestructure. In this embodiment, the first terminal 21 is taken as anexample for illustration. Specifically, the first terminal 21 includes:

an acquisition module 211, configured to acquire a wireless networktemporary identifier used for D2D communication and transmission grantinformation scrambled through the wireless network temporary identifierused for the D2D communication; and

a processing module 213, configured to perform the device to devicecommunication according to the descrambled transmission grantinformation.

The processing module 213 is further configured to perform the D2Dcommunication according to the descrambled transmission grantinformation, which specifically includes: performing, on a carrierindicated by the transmission carrier information, the device to devicecommunication according to the transmission grant information.

The acquisition module 211 is further configured to acquire thetransmission carrier information. For example, the acquisition module211 acquires the transmission carrier information sent by a basestation; or, the acquisition module 211 acquires the transmissioncarrier information according to the transmission grant information.

The transmission carrier information acquired by the acquisition module211 may be the transmission carrier information sent by the base station11 through an RRC message, may also be the transmission carrierinformation acquired according to the transmission grant information,such as the carrier indicated in the transmission grant information bythe base station 11.

The acquisition module 211 is further configured to acquire one wirelessnetwork temporary identifier used for the device to devicecommunication; and the transmission grant information includes device todevice transmission direction indication information.

Specifically, after descrambling, by using the acquired wireless networktemporary identifier used for the D2D communication, the scrambledtransmission grant information sent by the base station, the processingmodule 213 establishes a D2D communication connection, and sends orreceives data according to a transmission direction indicated by the D2Dtransmission direction indication information included in thetransmission grant information. For example, when the directionindicated by the transmission grant information descrambled by the firstterminal 21 is from the first terminal 21 to the second terminal 22, thefirst terminal 21 sends the data. For another example, when thedirection indicated by the transmission grant information descrambled bythe first terminal 21 is from the second terminal to the first terminal,the first terminal 21 receives the data.

Alternatively, the acquisition module 211 is further configured toacquire two wireless network temporary identifiers used for the deviceto device communication; and the wireless network temporary identifierwhich is sent by the base station 11 and used for the device to devicecommunication is applicable to a device to device transmissiondirection.

Specifically, the acquisition module 211 may acquire two wirelessnetwork temporary identifiers which are configured by the base station11 and used for the D2D communication; the processing module 213determines the D2D transmission direction according to a value of thewireless network temporary identifier used for the D2D communication.For example, when the value configured for the first wireless networktemporary identifier used for the D2D communication is 100 and the valueconfigured for the second wireless network temporary identifier used forthe D2D communication is 200, if in the processing module 213, thedescrambled transmission grant information is obtained by descramblingthrough the identifier with the value of 100, an applicable D2Dtransmission direction is determined to be from the first terminal 21 tothe second terminal 22, and the first terminal 21 sends the data; if thedescrambled transmission grant information is obtained by descramblingthrough the identifier with the value of 200, the applicable D2Dtransmission direction is determined to be from the second terminal 22to the first terminal 21, and the first terminal 21 receives the data.The transmission direction which is corresponding to the value of thewireless network temporary identifier used for the D2D communication maybe obtained through negotiation between the base station 11 and theterminal

Alternatively, the acquisition module 211 is further configured toacquire cell wireless network temporary identifiers of the firstterminal and the second terminal; and the transmission grant informationincludes the device to device communication indication information. TheD2D communication indication information included in the transmissiongrant information is used for explaining to the first terminal 21 thatthe grant information is used for the D2D transmission. When theindication is not included, the first terminal 21 determines that thegrant information is used for authorizing the transmission between theterminal and the base station, but not used for authorizing transmissionof the D2D communication.

Specifically, the cell wireless network temporary identifiers of thefirst terminal 21 and the second terminal 22 may be configured to act asthe wireless network temporary identifiers used for the D2Dcommunication. When the D2D communication is performed according to thecell wireless network temporary identifiers, the acquisition module 211needs to simultaneously acquire the cell wireless network temporaryidentifiers of the first terminal 21 (a local end) and the secondterminal 22 (a peer end). The scrambled transmission grant informationis descrambled by using the cell wireless network temporary identifierof the local end or of the peer end, and the processing module 213performs the D2D communication with the second terminal 22 according tothe descrambled transmission grant information. The first terminal 21further includes a sending module 215 configured to: when thetransmission grant information is obtained by descrambling through thecell wireless network temporary identifier of the first terminal 21,send the data to the second terminal 22 according to the transmissiongrant information; the acquisition module 211 is further configured to:when the transmission grant information is obtained by descramblingthrough the cell wireless network temporary identifier of the secondterminal 22, receive, according to the transmission grant information,the data sent by the second terminal.

By sending, to the terminal, the wireless network temporary identifierused for performing the device to device communication and thetransmission grant information, the terminal may realize the D2Dcommunication according to the wireless network temporary identifierused for performing the device to device communication and thetransmission grant information, thereby satisfying a requirement of D2Ddata transmission between users.

Furthermore, before sending the transmission grant information, the basestation 11 is further configured to notify the first terminal 21 and thesecond terminal 22 of a mapping between logical channels of the deviceto device communication of the first terminal 21 and the second terminal22. The acquisition module 211 in the first terminal 21 is furtherconfigured to acquire the mapping, which is sent by the base station andbetween the logical channels of the device to device communication. Forexample, the first terminal 21 needs to transfer a file to the secondterminal 22 according to a file transfer protocol, and for the filetransfer service, logical channel identifiers allocated to the firstterminal 21 and the second terminal 22 by the base station 11 are 3 and4 respectively. In this situation, the base station 11 needs toassociate the logical identifier of 3 of the first terminal 21 with thelogical identifier of 4 of the second terminal 22, and notify the twoterminals of the mapping to enable the first terminal 21 and the secondterminal 22 to receive and send data and to perform acknowledgementcorrectly. For another example, the base station 11 may allocate thesame logical channel identifier to the same service of the D2Dtransmission performed by the two terminals. According to the mappingsent by the base station, the D2D communication may be better performedbetween the first terminal 21 and the second terminal 22.

Furthermore, as shown in FIG. 2, the sending module 215 of the firstterminal 21 is further configured to: when the terminal is a sender andbefore the acquisition module 211 receives the transmission grantinformation scrambled through the wireless network temporary identifierused for the device to device communication, send buffer status of thelogical channel of the device to device communication to the basestation 11.

Before receiving the transmission grant information sent by the basestation 11, if the first terminal 21 acts as a sender, the firstterminal 21 may send, through the sending module 215, buffer status ofthe logical channel of the D2D communication to the base station 11.Specifically, the sending module 215 may indicate buffer status of thelogical channel of the D2D transmission to the base station 11 by usinga buffer status report (buffer status report, BSR for short) or anindependent component in the BSR, such as buffer status corresponding toan independent logical channel group.

Furthermore, as shown in FIG. 2, the acquisition module 211 of the firstterminal 21 is further configured to: when the second terminal 22 is areceiver, the first terminal 21 is a sender, and the second terminal 22detects that radio link control serial numbers on the logical channelare out of order, receive radio link control RLC information sent by thesecond terminal 22; and the first terminal 21 further includes aretransmission module 216, configured to retransmit data to the secondterminal 22 according to the RLC information.

Through the acquisition module 211 and the retransmission module 216,when an abnormality occurs during the D2D communication between thefirst terminal 21 and the second terminal 22, data retransmission isperformed, so as to ensure the accuracy and completeness of data of theD2D transmission.

Furthermore, during the D2D communication, the first terminal 21 or thesecond terminal 22 is further configured to send a D2D transmissionreport to the base station 11. Specifically, the sending module 215 ofthe first terminal 21 is further configured to send the device to devicetransmission report to the base station 11. The device to devicetransmission report includes a report type indication. The report typeindication may be at least one piece of the following information:device to device transmission failure information, device to devicetransmission completion information, and device to device transmissionformat adjustment information. For example, the device to devicetransmission format adjustment information may be used for indicating adevice to device transmission situation, may also be used for indicatingan adjustment on a modulation and coding scheme (modulation and codingscheme, MCS for short) of the current transmission and/or an adjustmenton a data transmission power scheme.

The sending module 215 of the first terminal 21 may periodically sendthe D2D transmission report to the base station 11 according to time setby a timer. The timer may be configured by the base station 11. The basestation 11 may indicate, according to the report type indication of D2Dtransmission failure or D2D transmission format adjustment in thetransmission report, a new modulation and coding scheme (modulation andcoding scheme, MCS for short) and/or data transmission power in anuplink grant sent to the first terminal 21, so as to instruct the firstterminal 21 to adjust the MCS and/or the data transmission power beforeperforming the data transmission. The first terminal 21 is furtherconfigured to: after receiving the device to device transmission formatadjustment indication sent by the base station 11, when receiving againupdated transmission grant information scrambled through the wirelessnetwork temporary identifier used for the device to devicecommunication, restart the timer for retiming, so as to send the deviceto device transmission report to the base station 11.

The first terminal 21 may further send the D2D transmission report tothe base station 11 when detecting that the number or proportion ofabnormalities incurred to data transmission on the logical channelexceeds a preset threshold; or, when the number of data retransmissionsreaches the preset maximum number of retransmissions, send the D2Dtransmission report to the base station 11, where the preset thresholdfor the number of abnormalities incurred to data transmission or thepreset maximum number of retransmissions for the number of dataretransmissions may be configured and then sent to the first terminal 21by the base station 11. A specific manner in which the first terminal 21sends the D2D transmission report may be selected according to actualneeds.

If a report type of the D2D transmission report received by the basestation 11 is D2D communication failure or D2D communication completion,the base station 11 may switch the logical channel of the D2Dcommunication to an air interface transmission manner.

By sending the report to the base station for a notification of thetransmission situation, the base station is enabled to adjust the MCSand/or the data transmission power of the D2D communication between thefirst terminal and the second terminal according to the report at anytime, so as to better realize D2D communication between the firstterminal and the second terminal.

Furthermore, at the end of the D2D communication, the first terminal 21may further perform hybrid automatic repeat request (hybrid automaticrepeat request, HARQ for short) perform acknowledgement with the secondterminal 22, and perform HARQ retransmission. In order to simplify therealization of the terminal, the base station 11 may set the number ofHARQ transmissions of the D2D transmission as 1, and notify the firstterminal 21 and the second terminal 22 of the number, so that a complexphysical uplink control channel (physical uplink control channel, PUCCHfor short) designed for the D2D transmission may be avoided.

After the D2D communication ends, the HARQ acknowledgement is performed,so as to facilitate performing of the HARQ retransmission, and furtherensure the accuracy and completeness of data of the D2D transmission,thereby better realizing the D2D communication.

A method for realizing device to device transmission of the presentinvention is described in detail in the following.

FIG. 3 is a schematic flow chart of Embodiment 1 of a method forrealizing device to device transmission of the present invention. Themethod in this embodiment includes:

S101: Acquire a wireless network temporary identifier used for device todevice communication;

S102: Receive transmission grant information scrambled through thewireless network temporary identifier used for the device to devicecommunication; and

S103: Perform the device to device communication according to thedescrambled transmission grant information.

In this embodiment, terminals performing the D2D communication include afirst terminal and a second terminal The first terminal and the secondterminal both execute the aforementioned steps from S101 to S103. Thefirst terminal is taken as an example for illustration.

The first terminal acquires the wireless network temporary identifierused for the D2D communication in step S101, which includes: acquiringone wireless network temporary identifier used for the D2Dcommunication; and the transmission grant information includes device todevice transmission direction indication information.

Specifically, in step S103 after descrambling, by using the acquiredwireless network temporary identifier used for the D2D communication,the scrambled transmission grant information received in step S102, aD2D communication connection is established in step S103, and data issent or received according to a transmission direction indicated by thedevice to device transmission direction indication information includedin the transmission grant information. For example, when the directionindicated by the transmission grant information descrambled by the firstterminal is from the first terminal to the second terminal, the firstterminal 21 sends the data. For another example, when the directionindicated by the transmission grant information descrambled by the firstterminal is from the second terminal to the first terminal, the firstterminal receives the data.

Alternatively, the first terminal acquires the wireless networktemporary identifier used for the D2D communication in step S101, whichincludes: acquiring two wireless network temporary identifiers used forthe D2D communication; and the acquired wireless network temporaryidentifiers used for the device to device communication are applicableto a device to device transmission direction.

Specifically, in step S101, two wireless network temporary identifiersused for the D2D communication may be acquired; in step S103, the D2Dtransmission direction is determined according to values of the wirelessnetwork temporary identifiers used for the D2D communication. Forexample, when the value configured for the first wireless networktemporary identifier used for the D2D communication is 100 and the valueconfigured for the second wireless network temporary identifier used forthe D2D communication is 200, if the transmission grant information isobtained by descrambling through the identifier with the value of 100,the applicable D2D transmission direction determined in step S103 isfrom the first terminal to the second terminal, and the first terminalsends the data; if the transmission grant information is obtained bydescrambling through the identifier with the value of 200, theapplicable D2D transmission direction determined in step S103 is fromthe second terminal to the first terminal, and the first terminalreceives the data.

Alternatively, the first terminal acquires the wireless networktemporary identifier used for the D2D communication in step S101, whichincludes: acquiring cell wireless network temporary identifiers of thefirst terminal and the second terminal; and the transmission grantinformation includes device to device communication indicationinformation. The cell wireless network temporary identifiers of thefirst terminal and the second terminal may be configured to act as thewireless network temporary identifiers used for the D2D communication.The D2D communication indication information included in thetransmission grant information is used for explaining to the firstterminal that the grant information is used for the D2D transmission.When the indication is not included, the first terminal determines thatthe grant information is used for authorizing the transmission betweenthe terminal and a base station, but not used for authorizingtransmission of the D2D communication.

Specifically, when the D2D communication is performed according to thecell wireless network temporary identifiers, the cell wireless networktemporary identifiers of the first terminal (a local end) and the secondterminal (a peer end) need to be acquired simultaneously in step S101.The scrambled transmission grant information is descrambled by using thecell wireless network temporary identifier of the local end or of thepeer end; the first terminal performs the D2D communication with thesecond terminal according to the descrambled transmission grantinformation. When the transmission grant information is obtained bydescrambling through the cell wireless network temporary identifier ofthe first terminal, the first terminal sends the data to the secondterminal according to the transmission grant information; when thetransmission grant information is obtained by descrambling through thecell wireless network temporary identifier of the second terminal, thefirst terminal receives, according to the transmission grantinformation, the data sent by the second terminal.

By sending, to the terminal, the wireless network temporary identifierused for performing the device to device communication and thetransmission grant information, the terminal may realize the D2Dcommunication in a simple and quick way according to the wirelessnetwork temporary identifier used for performing the device to devicecommunication and the transmission grant information, thereby satisfyinga requirement of D2D data transmission between users.

FIG. 4 is a schematic flow chart of Embodiment 2 of a method forrealizing device to device transmission of the present invention. Inthis embodiment, terminals need to perform D2D communication include afirst terminal and a second terminal. The method includes:

S201: Acquire a wireless network temporary identifier used for device todevice communication;

S202: Receive transmission grant information scrambled through thewireless network temporary identifier used for the device to devicecommunication;

S203: Perform the device to device communication according to thedescrambled transmission grant information;

S204: In a communication process, when the second terminal is a sender,the first terminal is a receiver, and the first terminal detects thatradio link control serial numbers on a logical channel are out of order,the first terminal sends radio link control RLC information to thesecond terminal as an acknowledgement; and

S205: The first terminal receives the data retransmitted according tothe RLC information by the second terminal.

Further alternatively, before step S202, the method may furtherincludes: acquiring a mapping which is between the logical channels ofthe device to device communication and sent by a base station; when thefirst terminal or the second terminal is the sender, sending, by thefirst terminal or the second terminal, buffer status of the logicalchannel of the device to device communication to the base station.

Further alternatively, in the D2D communication process performed instep S203, the method further includes: sending, by the first terminalor the second terminal, a device to device transmission report to thebase station. The device to device transmission report includes a reporttype indication, where the report type indication is at least one pieceof the following information: device to device transmission failureinformation, device to device transmission completion information, anddevice to device transmission format adjustment information.

Further alternatively, after the device to device transmission iscompleted, the method further includes: performing, by the firstterminal and the second terminal, HARQ acknowledgement and HARQretransmission.

In this embodiment, the RLC serial number detection performed on thelogical channel in the D2D communication process and the dataretransmission performed when data is transmitted out of order canensure the accuracy and completeness of data of the D2D transmission.

FIG. 5 is a schematic flow chart of Embodiment 3 of a method forrealizing device to device transmission of the present invention. Inthis embodiment, terminals need to perform D2D communication include afirst terminal and a second terminal. The method includes:

S301: Acquire a wireless network temporary identifier used for device todevice communication;

S302: Acquire a mapping which is between logical channels of the deviceto device communication and sent by a base station;

S303: When the first terminal or the second terminal is a sender, thefirst terminal or the second terminal sends buffer status of the logicalchannel of the device to device communication to the base station;

S304: Receive transmission grant information scrambled through thewireless network temporary identifier used for the device to devicecommunication; and

S305: Perform the device to device communication according to thedescrambled transmission grant information.

In this embodiment, the mapping which is between the logical channelsand sent by the base station is acquired before establishing the D2Dcommunication, and the first terminal or the second terminal that actsas the sender sends buffer status of the logical channel of the deviceto device communication to the base station, thereby better realizingthe D2D communication from the first terminal to the second terminal.

FIG. 6 is a schematic flow chart of Embodiment 4 of a method forrealizing device to device transmission of the present invention. Inthis embodiment, terminals need to perform D2D communication include afirst terminal and a second terminal. The method includes:

S401: In a D2D communication process performed by the first terminal andthe second terminal, when the second terminal is a sender, the firstterminal is a receiver, and the first terminal detects that radio linkcontrol serial numbers on a logical channel are out of order, the firstterminal sends radio link control RLC information to the second terminalas an acknowledgement; and

S402: The first terminal receives data retransmitted according to theRLC information by the second terminal.

In this embodiment, the RLC serial number detection performed on thelogical channel in the D2D communication process and the dataretransmission performed when data is transmitted out of order canensure the accuracy and completeness of data of the D2D transmission.

FIG. 7 is a schematic flow chart of Embodiment 5 of a method forrealizing device to device transmission of the present invention. Inthis embodiment, terminals need to perform D2D communication include afirst terminal and a second terminal. The method includes the followingsteps.

S501: In a D2D communication process performed by the first terminal andthe second terminal, send a device to device transmission report to abase station, where the device to device transmission report includes areport type indication.

The report type indication is at least one piece of the followinginformation:

device to device transmission failure information;

device to device transmission completion information; or

device to device transmission format adjustment information.

For example, the device to device transmission format adjustmentinformation may be used for indicating a device to device transmissionsituation, may also be used for indicating an adjustment on a modulationand coding scheme (modulation and coding scheme, MCS for short) of thecurrent transmission and/or an adjustment on a data transmission powerscheme.

The sending the device to device transmission report to the base stationincludes: sending the device to device transmission report to the basestation according to time set by a timer.

Specifically, the timer is started after a D2D transmission reportperiod configured by the base station is received; when the timerexpires, the device to device transmission report is sent to the basestation. For example, the number or proportion of HARQ or RLCtransmission failures within the period is reported.

Alternatively, the sending the device to device transmission report tothe base station includes: when detecting that the number or proportionof abnormalities incurred to device to device communication on thelogical channel exceeds a threshold, sending the device to devicetransmission report to the base station.

Specifically, the D2D transmission report threshold configured by thebase station is received, where the D2D transmission report thresholdmay be the number or proportion of the HARQ or RLC transmissionfailures. The device to device transmission report is sent to the basestation after the D2D transmission report threshold is reached, forexample, the number or proportion of HARQ or RLC transmission failureswithin the period is reported, or that the threshold is reached issimply indicated.

Alternatively, the sending the device to device transmission report tothe base station includes: when the number of the device to device dataretransmissions reaches the preset maximum number of retransmissions,sending the device to device transmission report to the base station.

Specifically, the maximum number of RLC transmissions or the maximumnumber of retransmissions configured by the base station is received;when the number of the D2D transmissions reaches the maximum number ofRLC transmissions or the maximum number of retransmissions or the D2Dtransmission is completed, the device to device transmission report issent to the base station, for example, D2D transmission failure, D2Dtransmission completion, or D2D transmission completion request isreported.

S502: Receive updated transmission grant information scrambled throughthe wireless network temporary identifier used for the device to devicecommunication.

The base station may update, according to the transmission report, thetransmission grant information scrambled through the wireless networktemporary identifier used for the device to device communication, andindicates a new MCS and/or data transmission power in the transmissiongrant information, so as to instruct the first terminal and the secondterminal to adjust the MCS and/or data transmission power beforeperforming the data transmission. The first terminal or the secondterminal is further configured to: after receiving the device to devicetransmission format adjustment indication sent by the base station, whenreceiving again the updated transmission grant information scrambledthrough the wireless network temporary identifier used for the device todevice communication, restart the timer for retiming, so as to send thedevice to device transmission report to the base station.

If the type of the D2D transmission report received by the base stationis the device to device transmission failure or device to devicetransmission completion, the base station switches the logical channelof the device to device transmission to an air interface transmissionmanner.

The manner used by the first terminal or the second terminal to send theD2D transmission report may be selected according to actual needs.

In this embodiment, the transmission grant information is updatedaccording to the D2D transmission report, so as to perform the D2D dataretransmission, and further ensure the accuracy and completeness of dataof the D2D transmission, better realizing the D2D communication.

FIG. 8 is a schematic flow chart of Embodiment 6 of a method forrealizing device to device transmission of the present invention. Inthis embodiment, terminals need to perform D2D communication include afirst terminal and a second terminal. The method includes:

S601: At the end of D2D communication performed by the first terminaland the second terminal, the first terminal and the second terminalperform HARQ acknowledgement; and

S602: The first terminal and the second terminal perform HARQretransmission.

Specifically, the second terminal acting as a receiver performs the HARQacknowledgement with the first terminal, and the first terminal performsthe D2D HARQ retransmission according to the HARQ acknowledgement;alternatively, the second terminal acting as the receiver performs thehybrid automatic repeat request HARQ acknowledgement with the basestation, and according to the hybrid automatic repeat request HARQacknowledgement, the base station schedules the first terminal toperform the D2D HARQ retransmission.

In this embodiment, after the D2D communication ends, the HARQacknowledgement is performed so as to perform the HARQ retransmission,and further ensure the accuracy and completeness of data of the D2Dtransmission, better realizing D2D communication.

Persons skilled in the art may understand that all or a part of theprocesses of the methods in the embodiments may be implemented by acomputer program instructing relevant hardware. The program may bestored in a computer readable storage medium. When the program is run,the processes of the methods in the embodiments are performed. Thestorage medium may be a magnetic disk, an optical disk, a Read-OnlyMemory (Read-Only Memory, ROM), a Random Access Memory (Read-OnlyMemory, RAM), and the like.

The above are merely exemplary embodiments of the present invention.However, the protection scope of the present invention is not limitedthereto. Therefore, equivalent changes derived according to the claimsof the present invention shall fall within the protection scope of thepresent invention.

What is claimed is:
 1. A method for realizing device to device (D2D) communication, comprising: sending, by a base station, a D2D identifier to at least two terminals; sending a transmission information scrambled by the D2D identifier to the at least two terminals by the base station, wherein the transmission information is used for D2D communication of the at least two terminals; wherein the transmission information is at least one kind of information: a carrier of the D2D communication, and a D2D transmission direction between the at least two terminals.
 2. The method according to claim 1, the method further comprising: sending a notification of a mapping between logical channels of the D2D communication of the at least two terminals by the base station.
 3. The method according to claim 1, wherein before the base station sends the transmission information, the method further comprises: receiving a notification of buffer status of at least one logical channel in a D2D sender of the at least two terminals by the base station, wherein the buffer status indicates an amount of to-be-transmitted data.
 4. The method according to claim 1, the method further comprising: receiving a transmission report from one of the at least two terminals by the base station, wherein the transmission report comprises at least one of the following: a request of modulation and coding scheme (MCS) adjustment of the D2D communication, and information indicating a failure of the D2D communication or a completion of the D2D communication.
 5. The method according to claim 1, wherein the D2D identifier is a wireless network temporary identifier used for the D2D communication of the at least two terminals.
 6. A base station, comprising: a transmitter, a receiver and a processor coupled to the transmitter and the receiver; wherein the transmitter is configured to send a D2D identifier to at least two terminals; the transmitter is further configured to send a transmission information scrambled by the D2D identifier to the at least two terminals, wherein the transmission information is used for D2D communication of the at least two terminals; wherein the transmission information is at least one kind of information: a carrier of the D2D communication, D2D transmission direction between the at least two terminals.
 7. The base station according to claim 6, wherein the transmitter is further configured to send a notification of a mapping between logical channels of the D2D communication of the at least two terminals.
 8. The base station according to claim 6, wherein the receiver is configured to receive a notification of buffer status of at least one logical channel in a D2D sender of the at least two terminals before the base station sends the transmission information, wherein the buffer status indicates an amount of to-be-transmitted data in the D2D communication.
 9. The base station according to claim 6, wherein the receiver is configured to receive a transmission report from one of the at least two terminals, wherein the transmission report comprises at least one of the following: a request of modulation and coding scheme (MCS) adjustment of the D2D communication, information indicating a failure of the D2D communication or a completion of the D2D communication.
 10. The method according to claim 6, wherein the D2D identifier is a wireless network temporary identifier used for the D2D communication of the at least two terminals. 